Endoscope systems are widely used for medical diagnosis. To observe organs in a body cavity, an elongated portion of an endoscope system is inserted into the body cavity. Then, according to the need, a treatment instrument may be inserted into an insertion passage to perform various therapeutic treatments. For the cleaning and treatment of a treated portion in the body cavity or for expanding the body cavity to increase a field of view, the endoscope is provided with a gas/liquid supply device that can feed, based on the need, water, medical liquid and/or air into the body cavity.
In the prior art, the gas/liquid supply device of the endoscope is controlled by a fluid control valve disposed on an operation portion of the endoscope. A gas inlet for gas feeding, a liquid inlet for liquid feeding, a gas outlet for gas discharge and a liquid outlet for liquid discharge of the endoscope are all disposed on the liquid control valve, with a button thereon to control the feeding of gas and liquid. Due to the limited space in the insertion tube of the endoscope, liquids and gases into the human body, the same pipeline in the insertion tube is used to feed gas and/or liquid into the human body. The liquid outlet and gas outlet extend from the fluid control valve and into an affected area up front, through a three-way tee into the same pipeline and through the insertion tube of the endoscope.
In order to prevent contamination of the fluid control valve, liquid source or gas source due to backflow of bodily fluids, a one-way check valve is provided at an output of the three-way tee. This is to prevent backflow of bodily fluids to the fluid control valve.
In the structure of the fluid control valve of the aforementioned prior art endoscope, the fluid outlet and the gas outlet of the fluid control valve are separate from each other in addition to the need of the three-way tee and check valve. This results in complicated structure as well as increased hardware cost. Moreover, the check valve may be clogged by impurities and thus requires frequent cleaning. As the check valve is disposed inside the operation portion of the endoscope, the need for opening up the operation portion for cleaning tends to cause inconvenience.